Pacific glass sponges and reefs

Glass sponges are globally unique ecosystems. 200 million years ago, glass sponge reefs were common world-wide. They were thought to have gone extinct approximately 40 million years ago; however, live reefs were discovered in 1987 by Canadian scientists in a few locations off the Pacific Coast of Canada and the United States of America.

In British Columbia, glass sponge reefs are found in Hecate Strait, Queen Charlotte Sound, the Strait of Georgia and Howe Sound and typically reside at depths of 90 to 300 metres. In Howe Sound they can be found as shallow as 22 metres. These reefs can grow to cover hundreds of square kilometers of the sea floor and be as tall as 25 metres high.

About glass sponge reefs

Glass sponge reefs are some of the oldest animals on earth, providing habitat for hundreds of species and filtering vast quantities of bacteria from the ocean. Some species of glass sponge, including the cloud sponge (Aphrocallistes vastus) and the goblet sponge (Heterchone calyx) are reef building sponges, meaning that new generations of glass sponges settle on the rigid skeletons left by previous generations, creating mounds or reefs, eventually growing into the structures found on the ocean floor today. The Hecate Strait reefs are some of the largest living glass sponge reefs known to date.

Glass sponge reefs are a slow growing species, only 1 to 2 cm per year, and have rigid skeletons made entirely of silica (glass), making them incredibly fragile. This makes them susceptible and vulnerable to damage from bottom-contact activities and sediment build-up. Broken reefs may take tens to hundreds of years to regrow while sediment can prevent new sponge growth and suffocate current sponge, ultimately weakening the reef over time.

Why glass sponge reefs are important

Glass sponge reefs are incredibly important to biodiversity and the health of the ocean because they:

• Provide refuge, habitat, food and nursery areas for over 120 aquatic species such as rockfish, sea stars, crabs and prawns. This results in species being 3 times more biodiverse within the reefs than outside of them
• Process vast amounts of organic carbon and nitrogen in the water (<436kg/day)
• Harness excess silica (i.e., glass) from the water column to help build the reefs
• Filter more than 800 times their body volume every hour

Bottom-contact fishing activities and anchoring pose a threat to glass sponge reefs as bottom-contact gear can break a reef or stir up sediment. Protecting the reefs through conservation efforts is one of the ways we can preserve the ecosystems for the long-term.

Glass sponge reef protections

Some of the ways glass sponge reefs are protected include:

• Fisheries closures that prohibit fishing activities that pose a risk to the glass sponge reefs
• Establishing marine refuges to protect species and their habitats from the impacts of fishing and other harmful marine activities
• Designating Marine Protected Areas to legally protect and manage sites for long-term conservation

Many of the glass sponge reefs in the Strait of Georgia and Howe Sound are protected through the establishment of marine refuges and fisheries area closures. You must follow Canada’s laws and regulations when fishing and boating within the marine refuges.

To report a potential fisheries violation, you can contact our 24/7 toll-free Observe, Record, Report line at 1-800-465-4336 or DFO.ORR-ONS.MPO@dfo-mpo.gc.ca.